1. Pay for a listing (Google Adwords, Yahoo directory listing, Inktomi paid inclusion, Overture pay-per-click, etc)
2. *Get picked up by search engine crawlers/spiders
3. **Work to constantly maintain/grow/improve your crawler gained listing.
4. ***Illegitimate search engine spamming

* Most search engines (Google for example) obtain their normal unpaid listing through a process called "spidering" or "crawling". A "crawler" is a computer program that simulates a web browser surfing the web, clicking through various links. The crawler indexes and catalogs the pages it views and then when someone searches for a term on a search engine, the search term is checked against the indexed pages. Being "crawled" isn't really something you can force to happen - chances are very strong that it will happen all on it's own. To improve the accuracy of your crawled result, do things like:

• Using key words throughout your site - particularly your front page. Try to use text instead of images as crawlers can't read text on images. If you sell televisions, you'll want to use the word television, TV, and television brand names in the copy on your site, particularly your front page.
• Use "alt tags" on your images. This helps crawlers identify key words that might be embedded in images (and therefore unreadable by crawlers). Using alt-text for your images is not only a great idea for search engine placement, but it helps address accessibility issues. For example - vision impaired visitors won't see your images, but their "web reader" software will be able to read your alt tags and help them get a better "picture" of what your site offers.
• Use a good descriptive title for your pages (home page esp.) For your Acme TV site a title like "Acme TVs - selling televisions from Sony, Zenith and Panasonic" would do the trick.
• Put descriptive text as the initial text on your front page. Many search engines also list a tiny excerpt of text in their search results. On several search engines, the excerpt of text they use is the first little bit of copy they find on the indexed page, so have it be something that will entice visitors to click over to your site.
• Use META keywords and descriptions. Note that while in the past this was widely used by crawlers, it really has become nearly obsolete. Much hand-wringing is wasted on panic around having META keywords in place when truthfully - it's not quite a waste of time, but almost. That's because most crawlers have stopped using them due to abuse by users. If your search engine marketing company is putting a bunch of eggs in this basket - be leery - chances are they haven't updated their methods for a few years.
• Get sites to link to you (and then link back to them if it makes sense). Getting other sites to link to yours plays specifically into the hand of the Google PageRank algorithm. This is the algorithm that determines how "high up" in the listings a certain result will be. Note that there's whispering that this algorithm may undergo some tweaking due to "trackback" and other blog related cross-linking that are gumming up the works, but at least for now that does help you increase the visibility of your site.

**To maintain your crawler gained listing takes a fair amount of work. At least every couple of weeks a whole process of testing results and tweaking things to improve it is needed. If you've got a webmaster that can do this regularly - it may be worth the investment to keep those listings strong.

***Search engine spamming is a bad idea.
Using tricks like:

• hidden text and links


• mirror pages and sites


• doorway pages


• cloaking


• link farming


• automated submission and query tools

Don't let anyone talk you into employing these tactics, not only is it ethically marginal - it can lead to outright banning of your listing by a search engine who becomes wise to your methods. Don't tempt fate! Doing this can bring exactly the opposite result you are seeking.

Finally - a word about search engine marketing in the overall scheme of online marketing.
Search engine marketing is, and can be very powerful at helping you get new visitors, but remember that your best money is still spent improving the relationship you already have with your existing customers (online and off) and wisely and ethically cultivating that resource for new leads and new business. Depending on your business, my advice is always to put some resources into search engine marketing, but never to the exclusion of more effective long lasting marketing efforts designed to help you create a sustained customer base that you can count on for generations to come.

[Update 12/16 some more corroborating information]